Device for catalytic conversion having a reduced activation time

Abstract

A device for catalytic conversion of NOx to 8 and / or of CO to CO2, including: a ceramic support including at least a plurality of channels; a thermal barrier made of thermal insulating material covering at least one part of the internal surface of the channels; porous SiC at least partially covering the thermal barrier such that the SiC is separated from the support by the thermal barrier; one or more conversion catalysts at least on the SiC.

Description

TECHNICAL FIELD AND PRIOR ART[0001]This invention relates to a device for catalytic conversion having a reduced activation time, intended for the depollution of gases, in particular the depollution of exhaust gases of a motor vehicle.[0002]Internal combustion engines, in particular diesel engines, produce exhaust gases containing nitrogen oxides, routinely referred to as NOx, mainly composed of nitrogen monoxide NO and carbon monoxide CO.[0003]We are looking to reduce these polluting emissions.[0004]Depollution systems are provided on the exhaust line to treat the exhaust gases, in particular to reduce NOx into N2 and oxidise CO into CO2.[0005]One example of a depollution system includes a NOx trap. This trap comprises a reduction catalyst under diesel conditions, which requires the periodic supply of reducing agents via the engine (by post-injection of fuel), and generates a 60% to 70% reduction of NO, however causes an additional consumption of 2 g / km of CO2.[0006]This trap operat...

AI Technical Summary

Benefits of technology

The invention is a device for catalytic conversion that has better conversion efficiency and is easier to manufacture than previous devices. It uses a support made of a resistant, low-cost material, and only one layer of silicon carbide to help the catalysts get to their activation temperature faster. This results in faster treatment of exhaust gases on engine start-up and a continuous or substantially continuous treatment of the gases, leading to a significant reduction in the amount of pollutants released into the air.

Problems solved by technology

This trap comprises a reduction catalyst under diesel conditions, which requires the periodic supply of reducing agents via the engine (by post-injection of fuel), and generates a 60% to 70% reduction of NO, however causes an additional consumption of 2 g / km of CO2.

However, although the catalytic oxidation of the pollutants is not difficult within the highly-oxidising gaseous flow exiting the Diesel engine, the reduction of NOx into N2 in such an environment is incomplete.

However, this good thermal conductivity has the disadvantage of also causing a rapid drop in the temperature of the catalyst support.

Moreover, SiC is a fragile, expensive material.

These converters are complex to manufacture, and implement a thermoelectric generator and means for storing the electricity generated by the thermoelectric generator.

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